JP3388674B2 - Energy ray-curable pressure-sensitive adhesive composition and method of using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an energy ray-curable pressure-sensitive adhesive composition and a method of using the same. The energy ray-curable pressure-sensitive adhesive composition according to the present invention has sufficient adhesiveness to an adherend before irradiation with energy rays, and after irradiation with energy rays, adheres to an adherend after peeling. Curing to the extent that residual adhesive can be minimized is obtained, the expansion rate in the expanding process is high, and the recognition at the time of picking up is excellent. Is obtained,
High workability with or without expanding process. For this reason, the energy ray-curable pressure-sensitive adhesive composition according to the present invention is preferably used for applications premised on peeling after sticking, for example, a pressure-sensitive adhesive sheet for wafer processing or surface protection.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION Semiconductor wafers such as silicon and gallium arsenide are manufactured in a large diameter state, and after this wafer is cut and separated (dicing) into element small pieces, a step of mounting a chip on a lead frame from a bonding step. Moved to. At this time, each step of dicing, washing, drying, expanding, picking up, and mounting the chip and the lead frame in the state where the semiconductor wafer is stuck to the adhesive sheet is added.

As an adhesive sheet used in such processes from the dicing process of a semiconductor wafer to the pickup process, it has sufficient adhesive force to a wafer chip in the dicing process and adheres to the wafer chip at the time of pickup. It is desired that the agent does not adhere and has an adhesive strength such that it can be easily peeled off.

An example of such an adhesive sheet is Japanese Patent Laid-Open No.
0-196,956 and JP-A-60-223,
Japanese Patent No. 139 discloses a pressure-sensitive adhesive sheet having a substrate surface coated with a pressure-sensitive adhesive composed of a low-molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule, which can be three-dimensionally reticulated by light irradiation. Proposed. These proposals are pressure-sensitive adhesive tapes prepared by coating a radiation-curable adhesive on a radiation-transparent substrate. The radiation-curable compound contained in the pressure-sensitive adhesive is cured by irradiation with radiation to form a three-dimensional network on the adhesive. It is based on the principle of imparting a chemical structure and remarkably lowering its fluidity.

The conventional pressure-sensitive adhesive sheet as exemplified above has the following problems particularly in the expanding step and the pickup step. The expanding step is a step of widening the interval between the diced element pieces (chips) to facilitate chip pickup. When a conventional pressure-sensitive adhesive sheet for wafer sticking in which the residual amount of the pressure-sensitive adhesive is extremely reduced, curing of the pressure-sensitive adhesive layer progresses considerably and the pressure-sensitive adhesive layer becomes considerably hard. For this reason, the elongation rate (expansion rate) of the sheet becomes small, and it is difficult to obtain a desired chip interval. That is, a sufficient distance between adjacent chips cannot be obtained, which may cause recognition failure in the pickup process and cause malfunction.

Further, in the conventional adhesive tape as described above, since the adhesive layer is considerably hard, the holding property with the chip is deteriorated and the chip is misaligned at the time of pickup.
There was a case where the pickup was defective.

JP-A-5-214,298 discloses a pressure-sensitive adhesive prepared by adding a polyether compound having a relatively low molecular weight and an unsaturated oligomer having a relatively low molecular weight for imparting radiation curability. An adhesive sheet provided with an agent layer is taught. However, with this pressure-sensitive adhesive, if the amount of the low-molecular weight component added is too large, the initial pressure-sensitive adhesive strength will decrease, and chips will scatter during dicing. On the other hand, if the addition amount of the low molecular weight component is too small, there are drawbacks such that the adhesive force is not sufficiently reduced even when irradiated with radiation, or the amount of the adhesive remaining is large. Therefore, it was very difficult to control the adhesive property before and after irradiation with radiation.

Under the circumstances, the present inventors have completed the present invention as a result of earnest research to provide a pressure-sensitive adhesive composition which is further excellent in various functions such as curing characteristics.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, in which before the irradiation of energy rays,
It has a sufficient adhesive strength, and after irradiation it can be cured to such an extent that the amount of the adhesive remaining on the adherend after peeling can be extremely reduced, and the expansion rate in the expanding process is high, and at the time of pickup It is also an object of the present invention to provide an energy ray-curable pressure-sensitive adhesive composition which is excellent in recognizability and has high workability regardless of the presence or absence of an expanding step because an extremely low pickup force can be obtained in the bonding step. I am trying.

Another object of the present invention is to provide an adhesive sheet using such an energy ray-curable pressure-sensitive adhesive composition, particularly an adhesive sheet for wafer processing and an adhesive sheet for surface protection.

[0011]

SUMMARY OF THE INVENTION The energy ray-curable pressure-sensitive adhesive composition according to the present invention comprises (A) 100 g of an acrylic copolymer (a1) having a functional group-containing monomer unit, and a substitution that reacts with the functional group. Group-containing energy ray-polymerizable group-containing compound (a2)
An energy ray-curable copolymer having an energy ray-polymerizable group in a side chain and having a molecular weight of 50,000 or more, which is obtained by reacting with 0.12 mol or more, and (B) an acrylic resin having a functional group-containing monomer unit. Energy ray-polymerizable group-containing compound (b2) having a substituent reactive with the functional group, relative to 100 g of the copolymer (b1)
An energy ray-curable copolymer having a molecular weight of 50,000 or more and having an energy ray-polymerizable group in a side chain, which is obtained by reacting with less than 0.12 mol, and has an energy ray-polymerizable group in a side chain. It is characterized by not containing an acrylic polymer.

A photopolymerization initiator (C) may be further added to the above energy ray-curable pressure-sensitive adhesive composition. The pressure-sensitive adhesive sheet according to the present invention, the above energy ray-curable pressure-sensitive adhesive composition, the substrate is coated,
It is preferably used as an adhesive sheet for wafer processing or surface protection.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The energy ray-curable pressure-sensitive adhesive composition according to the present invention will be specifically described below.

The energy ray-curable pressure-sensitive adhesive composition according to the present invention comprises two or more energy ray-curable copolymers having an energy ray-polymerizable group in the side chain. (A) Energy ray curable copolymer, and (A)
Different from (B) energy ray-curable copolymer, and further contains (C) a photopolymerization initiator, if desired. The energy ray-curable pressure-sensitive adhesive according to the present invention
The agent composition does not have an energy ray-polymerizable group in the side chain.
It does not contain a kuriru polymer.

Hereinafter, particularly preferred examples of the (A) energy ray-curable copolymer, the (B) energy ray-curable copolymer, and the (C) photopolymerization initiator will be described in more detail. (A) Energy ray-curable copolymer The energy ray-curable copolymer (A) is an acrylic copolymer (a1) having a functional group-containing monomer unit and an energy having a substituent that reacts with the functional group. It is obtained by reacting with the linear polymerizable group-containing compound (a2).

The functional group-containing monomer is a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group and an epoxy group in the molecule, and preferably a hydroxyl group-containing monomer. An unsaturated compound and a carboxyl group-containing unsaturated compound are used.

More specific examples of such a functional group-containing monomer include 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, hydroxyl group-containing acrylate such as 2-hydroxypropyl methacrylate, acrylic acid,
Examples thereof include carboxyl group-containing compounds such as methacrylic acid and itaconic acid.

The above-mentioned functional group-containing monomers may be used alone or in combination of two or more. The acrylic copolymer (a1) is composed of a structural unit derived from the above functional group-containing monomer and a structural unit derived from a (meth) acrylic acid ester monomer or its derivative. As the (meth) acrylic acid ester monomer,
(Meth) acrylic acid cycloalkyl ester, (meth)
Acrylic acid benzyl ester, alkyl group has 1 carbon
A (meth) acrylic acid alkyl ester of -18 is used. Among these, particularly preferred are (meth) acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate. , Butyl acrylate, butyl methacrylate and the like are used.

The acrylic copolymer (a1) usually contains 1 to 100 structural units derived from the above functional group-containing monomer.
% By weight, preferably 2-80% by weight, particularly preferably 3
The content of the structural unit derived from the (meth) acrylic acid ester monomer or its derivative is usually 0 to 99% by weight, preferably 20 to 98% by weight.
Particularly preferably, the content is 50 to 97% by weight.

The acrylic copolymer (a1) can be obtained by copolymerizing the functional group-containing monomer as described above with a (meth) acrylic acid ester monomer or a derivative thereof by a conventional method. In addition to a small amount (for example, 10% by weight or less, preferably 5% by weight or less)
In the above ratio, vinyl formate, vinyl acetate, styrene, etc. may be copolymerized.

An energy ray-curable type is prepared by reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with the energy ray-polymerizable group-containing compound (a2) having a substituent reactive with the functional group. Copolymer (A)
Is obtained.

Energy ray-polymerizable group-containing compound (a2)
Contains a substituent capable of reacting with the functional group in the acrylic copolymer (a1). The substituent varies depending on the type of the functional group. For example, when the functional group is a hydroxyl group or a carboxyl group, the substituent is preferably an isocyanate group, an epoxy group or the like, when the functional group is an amino group or a substituted amino group, the substituent is preferably an isocyanate group or the like, When the functional group is an epoxy group, the substituent is preferably a carboxyl group. Such a substituent has an energy ray-polymerizable group-containing compound (a
2) One is included for each molecule.

Further, an energy ray-polymerizable group-containing compound (a
In 2), the energy ray-polymerizable group is 1 to 5 for each molecule.
, Preferably 1 to 2. As the energy ray-polymerizable group, there are a carbon-carbon double bond group, a carbon-carbon triple bond group, an epoxy group and the like, but a carbon-carbon double bond is preferably selected.

Specific examples of the energy ray-polymerizable group-containing compound (a2) include, for example, methacryloyloxyethyl isocyanate and meta-isopropenyl-.
α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; diisocyanate compound Or with a polyisocyanate compound,
Acryloyl monoisocyanate compound obtained by reaction of polyol compound and hydroxyethyl (meth) acrylate; glycidyl (meth) acrylate;
(Meth) acrylic acid and the like can be mentioned.

Energy ray-polymerizable group-containing compound (a2)
Is usually 0.12 mol or more, preferably 0.1 mol, per 100 g (solid content) of the acrylic copolymer (a1).
It is used in an amount of 2 to 1.0 mol, particularly preferably 0.12 to 0.5 mol.

The energy ray-polymerizable group-containing compound (a2) is usually 20 to 100 equivalents, preferably 45 to 95 equivalents, particularly preferably 100 equivalents of the functional group-containing monomer of the acrylic copolymer (a1). Is 60 ~
Used in a ratio of 90 equivalents.

The reaction between the acrylic copolymer (a1) and the energy ray-polymerizable group-containing compound (a2) is usually 2
It is carried out at a temperature of 0 ° C. to 50 ° C. and normal pressure for about 24 hours. This reaction is preferably carried out in a solution such as ethyl acetate using a catalyst such as dibutyltin laurate.

As a result, the functional group existing in the side chain in the acrylic copolymer (a1) and the substituent in the energy ray-polymerizable group-containing compound (a2) react with each other to form an energy ray-polymerizable group. It is introduced into the side chain in the acrylic copolymer (a1) to obtain the energy ray-curable copolymer (A). The reaction rate between the functional group and the substituent in this reaction is usually 80
% Or more, preferably about 90 to 100%, and unreacted functional groups may remain in the energy ray-curable copolymer (A).

The molecular weight of the energy ray-curable copolymer (A) is 50,000 or more, preferably 70,000.
0 to 1,500,000, particularly preferably 10
It is from 10,000 to 1,000,000. The glass transition temperature of the copolymer (A) is usually 20 ° C. or lower, preferably about −70 to 0 ° C., and it has tackiness at room temperature (23 ° C.).

Since the energy ray-curable copolymer (A) contains an energy ray-polymerizable group, it is polymerized and cured by irradiation with energy rays and loses its tackiness. (B) Energy ray-curable copolymer The energy ray-curable copolymer (B) is also an acrylic copolymer (b) having a functional group-containing monomer unit as described above.
It is obtained by reacting 1) with an energy ray-polymerizable group-containing compound (b2) having a substituent that reacts with the functional group. The specific examples of the acrylic copolymer (b1) are the same as the specific examples of the acrylic copolymer (a1) described above, and the specific examples of the energy ray-polymerizable group-containing compound (b2) are the same as the energy rays described above. It is the same as the specific example of the polymerizable group-containing compound (a2). However, the energy ray-curable copolymer (B) has a composition different from that of the energy ray-curable copolymer (A), and preferably the energy ray-curable copolymer (B) contains an energy ray-polymerizable group. The amount of the compound (b2) used is different from that of the energy ray-curable copolymer (A).

In preparing the energy ray-curable copolymer (B), the energy ray-polymerizable group-containing compound (b2)
Is usually less than 0.12 mol, preferably 0.0 per 100 g (solid content) of the acrylic copolymer (b1).
1 mol or more and less than 0.12 mol, particularly preferably 0.02
It is used in an amount of not less than 0.1 mol and not more than 0.12 mol.

The energy ray-polymerizable group-containing compound (b2) is usually 20 to 100 equivalents, preferably 45 to 95 equivalents, particularly preferably 100 equivalents of the functional group-containing monomer of the acrylic copolymer (b1). Is 60 ~
Used in a ratio of 90 equivalents.

The reaction between the acrylic copolymer (b1) and the energy ray-polymerizable group-containing compound (b2) is carried out under the same conditions as above. As a result, the functional group present in the side chain in the acrylic copolymer (b1) and the substituent in the energy ray-polymerizable group-containing compound (b2) react with each other, and the energy ray-polymerizable group becomes an acrylic copolymer. It is introduced into the side chain in the polymer (b1) to obtain the energy ray-curable copolymer (B). The reaction rate between the functional group and the substituent in this reaction is usually 80% or more, preferably about 90 to 100%, and the unreacted functional group remains in the energy ray-curable copolymer (B). May be.

The energy ray-curable copolymer (B) has a molecular weight of 50,000 or more, preferably 70,000.
0 to 1,500,000, particularly preferably 10
It is from 10,000 to 1,000,000. The glass transition temperature of the copolymer (B) is usually 20 ° C. or lower, preferably about −70 to 0 ° C., and it has tackiness at room temperature (23 ° C.).

Since the energy ray-curable copolymer (B) contains an energy ray-polymerizable group, it is polymerized and cured by irradiation with energy rays, and the adhesiveness is reduced.

The ratio of the component (A) and the component (B) in the energy ray-curable pressure-sensitive adhesive composition can be set arbitrarily, but is preferably A / B (weight ratio). Is 1/100 to 100/1, particularly preferably 1/50
It is desirable that it is ˜50 / 1, more preferably 1/10 to 10/1.

Such an energy ray-curable pressure-sensitive adhesive composition according to the present invention is cured by energy rays so that the amount of the adhesive remaining on the adherend after peeling can be extremely reduced. can get. Further, by using two or more polymers having an energy ray-polymerizable group in the side chain, the expansion rate in the expanding step becomes high, and the recognizability at the time of pickup is excellent. Further, in the bonding process, a very low pick-up force can be obtained, so that the workability is high regardless of the presence or absence of the expanding process. As the energy rays, specifically, ultraviolet rays, electron beams and the like are used. Further, the irradiation amount thereof varies depending on the type of energy ray, and for example, when ultraviolet rays are used, it is preferably about 40 to 200 W / cm,
When using an electron beam, about 10 to 1000 krad is preferable. The irradiation of such energy rays drastically reduces the adhesive strength. For example, the adhesive force to the mirror surface of a semiconductor wafer is 100 to 1000 g / before irradiation with energy rays.
Although it is about 25 mm, it is 0.5 before irradiation after irradiation.
It can be controlled to about 50%.

(C) Photopolymerization Initiator When ultraviolet rays are used as the energy rays, the photopolymerization initiator (C) is mixed in the above composition to reduce the polymerization curing time and the amount of light irradiation. can do.

As such a photopolymerization initiator (C),
Specifically, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1 -Hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-
Examples include crawl anthraquinone. The photopolymerization initiator (C) is used in an amount in the range of 0.1 to 10 parts by weight, particularly 0.5 to 5 parts by weight, based on 100 parts by weight of the total of (A) and (B). Is preferred.

Other Components In the energy ray-curable pressure-sensitive adhesive composition of the present invention, the above components (A) and (B), and if necessary, are used within a range not impairing the object of the present invention. in addition to the components (C) to be, in order to control the curing characteristics for energy ray, it can be added to the energy ray-polymerizable low molecular weight compound to the energy ray-curable pressure-sensitive adhesive composition. The molecular weight of the energy ray-polymerizable compound is 10,0
It is 00 or less, preferably about 100 to 8000.

Specific examples of the low molecular weight energy ray-polymerizable compound that can be used in the present invention include acrylate monomers, urethane acrylate oligomers,
Examples thereof include epoxy modified urethane acrylate oligomer and epoxy acrylate oligomer.

The low molecular weight energy ray-polymerizable compound is
The component (A) and the component (B) may be added in an amount of 0 to 100 parts by weight, particularly 0.1 to 10 parts by weight, based on 100 parts by weight in total. If the blending amount of the low molecular weight energy ray-polymerizable compound is too large, it becomes difficult to expand after curing, which is not preferable.

The energy ray-curable pressure-sensitive adhesive composition of the present invention contains an organic polyvalent isocyanate compound, an organic polyvalent epoxy compound, in order to adjust the initial adhesive force and cohesive force before irradiation with energy rays. It is also possible to add an organic polyvalent imine compound or the like.

As the organic polyvalent isocyanate compound, aromatic polyvalent isocyanate compounds, aliphatic polyvalent isocyanate compounds, alicyclic polyvalent isocyanate compounds and trimers of these polyvalent isocyanate compounds, In addition, a terminal isocyanate urethane prepolymer obtained by reacting these polyvalent isocyanate compounds with a polyol compound can be used. More specific examples of the organic polyvalent isocyanate compound include, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate and diphenylmethane-4. , 4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate And so on.

Specific examples of the organic polyvalent epoxy compound include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, 1,3-bis (N, N-diglycidylaminomethyl) benzene, 1,3-bis ( N, N-diglycidylaminomethyl) toluene, N, N, N ', N'-tetraglycidyl-4,
4-diaminodiphenylmethane etc. can be mentioned.

Specific examples of the organic polyvalent imine compound include N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate. , Tetramethylolmethane-
Tri-β-aziridinyl propionate, N, N'-toluene-
2,4-bis (1-aziridinecarboxamide) triethylenemelamine and the like can be mentioned.

Energy Ray-Curable Pressure-Sensitive Adhesive Composition The energy ray-curable pressure-sensitive adhesive of the present invention comprises the above-mentioned energy ray-curable copolymers (A) and (B), and optionally photopolymerization initiation. The agent (C) and the above-mentioned other components,
It can be obtained by mixing in a conventional manner.

Such an energy ray-curable pressure-sensitive adhesive composition can be cured by irradiation with energy rays to such an extent that the amount of the adhesive remaining on the adherend after peeling can be extremely reduced. Further, by using two or more polymers having an energy ray-polymerizable group in the side chain, the expansion rate in the expanding step becomes high, and the recognizability at the time of pickup is excellent. Further, in the bonding process, a very low pick-up force can be obtained, so that the workability is high regardless of the presence or absence of the expanding process. As the energy rays, specifically, ultraviolet rays, electron beams and the like are used. The amount of irradiation varies depending on the type of energy beam. For example, when ultraviolet rays are used, it is preferably about 40 to 200 W / cm, and when electron beams are used, it is preferably about 10 to 1000 krad. The irradiation of such energy rays drastically reduces the adhesive strength.
For example, the adhesive force to the mirror surface of the semiconductor wafer is about 100 to 1000 g / 25 mm before the irradiation of the energy rays, while it can be controlled to about 0.5 to 50% before the irradiation after the irradiation.

Method of Utilization The energy ray-curable pressure-sensitive adhesive composition of the present invention described above has sufficient tackiness to an adherend before irradiation with energy rays. On the other hand, after the irradiation with energy rays, curing can be obtained so that the amount of the adhesive remaining can be extremely reduced. Further, by using two or more polymers having an energy ray-polymerizable group in the side chain, the expansion rate in the expanding step during wafer processing becomes high, and the recognition at the time of pickup is also excellent. Further, in the bonding process, a very low pick-up force can be obtained, so that the workability is high regardless of the presence or absence of the expanding process. Therefore, this energy ray-curable pressure-sensitive adhesive is
It is preferably used for applications that require peeling after attachment.

The energy ray-curable pressure-sensitive adhesive sheet according to the present invention comprises a pressure-sensitive adhesive layer made of the energy ray-curable pressure-sensitive adhesive composition described above and a substrate. Examples of the substrate of the energy ray-curable pressure-sensitive adhesive sheet of the present invention include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film,
General-purpose films such as polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film Or a laminate of these is used.

When used for wafer processing having an expanding step, the substrate has a Young's modulus of preferably 250 to 5000 dyne / cm, more preferably 270 to 3000 dyne / cm, particularly preferably 300 to 1
It is preferably 500 dyne / cm, but the Young's modulus is not particularly limited when used for wafer processing without an expanding step.

When ultraviolet rays are used as the energy rays, a film having a transmittance of light having a wavelength of 300 to 400 nm of 5% or more, preferably 10% or more, more preferably 15% or more is used as the substrate. preferable.

Further, when an electron beam is used as the energy beam, it is not necessary to be transparent, and therefore, in addition to the above transparent film, an opaque film, a fluororesin film or the like obtained by coloring these can be used.

The energy ray-curable pressure-sensitive adhesive sheet of the present invention is obtained by applying the energy ray-curable pressure-sensitive adhesive composition onto various substrates according to generally known methods such as a comma coater, a gravure coater, a die coater and a reverse coater. Form an adhesive layer by coating and drying at an appropriate thickness,
Then, it is obtained by laminating a release sheet on the pressure-sensitive adhesive layer, if necessary.

The thickness of the pressure-sensitive adhesive layer varies depending on the use, but is usually 1 to 100 μm, preferably 5 to 50 μm.
m, particularly preferably about 10 to 30 μm. Also,
The thickness of the substrate is usually 10 to 300 μm, preferably 2
The thickness is 0 to 200 μm, particularly preferably 50 to 150 μm.

The energy ray-curable pressure-sensitive adhesive sheet according to the present invention may have any shape such as a tape shape and a label shape. When such an energy ray-curable pressure-sensitive adhesive sheet according to the present invention is attached to an adherend and then irradiated with energy rays, the adhesive force is drastically reduced. Therefore, the energy ray-curable pressure-sensitive adhesive sheet can be removed from the adherend without the residue of the pressure-sensitive adhesive remaining on the adherend.

Therefore, the energy ray-curable pressure-sensitive adhesive sheet according to the present invention is extremely suitable for use on the premise of peeling after sticking, and is used, for example, as a pressure-sensitive adhesive sheet for wafer processing or surface protection.

The pressure-sensitive adhesive sheet for surface protection is attached to the surface of a decorative plate, a glass plate, a metal plate, a plastic plate, etc., and protects the surface from being contaminated or damaged during transportation or processing. When protection is no longer necessary, it can be easily peeled off by irradiating with energy rays.

The wafer processing adhesive sheet is used for polishing the back surface of the wafer or for dicing. A large number of circuits are formed on the surface of a semiconductor wafer, and a semiconductor chip is manufactured by cutting and separating (dicing) each circuit. At this time, if the thickness of the wafer is not uniform or an oxide film is formed on the back surface, the performance of the obtained chips varies. Therefore, after the completion of the wafer process, the back surface of the wafer is polished, but polishing scraps may damage the circuit. In such a case, if the pressure-sensitive adhesive sheet for wafer processing according to the present invention is adhered to the surface of the wafer, damage to the circuit can be prevented. Moreover, by irradiating with energy rays, the adhesive sheet for wafer processing can be easily peeled off without leaving an adhesive, so that the wafer is not contaminated.
Moreover, the circuit is not destroyed at the time of peeling.

Similarly, at the time of dicing the wafer, the circuit may be damaged by cutting chips, and even in such a case, the circuit can be protected by the adhesive sheet for wafer processing of the present invention. Further, in order to hold the wafer stably during dicing, the wafer processing adhesive sheet of the present invention may be attached to the back surface of the wafer to fix the wafer.
According to such a wafer processing adhesive sheet of the present invention,
The wafer can be held with sufficient adhesive force before the irradiation with energy rays, and the adhesive force is drastically reduced when the energy rays are irradiated after dicing, so the semiconductor chip can be easily picked up without being contaminated by the adhesive. be able to. Moreover, the pressure-sensitive adhesive layer after irradiation with energy rays can be cured to such an extent that the amount of the pressure-sensitive adhesive remaining can be extremely reduced. Further, by using two or more polymers having an energy ray-polymerizable group in the side chain, the expansion rate in the expanding step during wafer processing becomes high, and the recognition at the time of pickup is also excellent. Further, in the bonding process, a very low pick-up force can be obtained, so that the workability is high regardless of the presence or absence of the expanding process.

[0061]

As described above, the energy ray-curable pressure-sensitive adhesive composition according to the present invention has sufficient adhesiveness to an adherend before irradiation with energy rays, and After irradiation, curing is obtained such that the residual amount of the pressure-sensitive adhesive can be extremely reduced. Further, by using two or more polymers having an energy ray-polymerizable group in the side chain, the expansion rate in the expanding step during wafer processing becomes high, and the recognition at the time of pickup is also excellent. Further, in the bonding process, a very low pick-up force can be obtained, so that the workability is high regardless of the presence or absence of the expanding process. For this reason, the energy ray-curable pressure-sensitive adhesive composition according to the present invention is preferably used for applications premised on peeling after sticking, for example, a pressure-sensitive adhesive sheet for wafer processing or surface protection.

[0062]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

In the following Examples and Comparative Examples, the "180 ° peeling adhesive force", "expandability (expansion rate)", "alignment", "residual particles" and "pickup force" are as follows. Evaluated. 180 ° Peeling Adhesive Strength The adhesive sheets obtained in Examples or Comparative Examples were
Under the atmosphere of 3 ° C. and 65% RH, the back surface of the semiconductor wafer (#
2000kg) by sticking a 2kg rubber roller back and forth, leaving it for 20 minutes, then a universal tensile tester (TENSILON / UTM-4-100, manufactured by Orientec Co., Ltd.)
Was used to measure the 180 ° peeling adhesive force at a peeling speed of 300 mm / min. In addition, after sticking under the same conditions and leaving it, irradiation distance of 10 cm with a high pressure mercury lamp (80 W / cm) from the base material sheet side,
After irradiating with ultraviolet rays at a line speed of 5 m / min, similarly 1
The 80 ° peel adhesion was measured. Expandability (expansion rate) A 5-inch silicon wafer was attached to an adhesive sheet, mounted on a flat frame, and fully cut into 10 mm square chips with a diamond blade having a thickness of 30 μm. Then 18
UV irradiation under the same conditions as when measuring the 0 ° peel adhesion,
The sheet was expanded by 10 mm using an expanding jig. At this time, the expansion rate of the entire wafer was measured. Alignment When the expansion ratio was measured, the chip arrangement was visually determined. A 4-inch silicon wafer was attached to the residual particle measurement adhesive sheet, left for 24 hours, and then irradiated with ultraviolet rays under the same conditions as in the 180 ° peel adhesive strength measurement to peel off the adhesive sheet. At this time, the number of particles remaining on the wafer was measured by a laser surface inspection device (manufactured by Hitachi Electronics Engineering). Pickup force measurement A 6-inch silicon wafer was attached to an adhesive sheet, mounted on a flat frame, and fully cut into 10 mm square chips with a diamond blade having a thickness of 30 μm. Then 18
UV irradiation was carried out under the same conditions as in the measurement of 0 ° peeling adhesive strength. Next, the sheet was fixed without expansion, a needle was attached to the tip of the push-pull gauge, the chip was pushed down from the back surface of the sheet, and the force at that time was measured at 10 points to obtain the average value.

In the following examples, the energy ray-curable copolymer (A), the energy ray-curable copolymer (B), the photopolymerization initiator (C) and the energy ray-free polymerizable group-free copolymer are used. The following were used as the polymer (D), the energy ray-polymerizable compound (E) and the crosslinking agent (F). Energy ray-curable copolymer (A) (A1): a weight average molecular weight of 400,000 including 60 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate, and 30 parts by weight of 2-hydroxyethyl acrylate.
A reaction product of 100 parts by weight of a 25% ethyl acetate solution of the copolymer of (1) and 7.5 parts by weight of methacryloyloxyethyl isocyanate (0.19 mol based on 100 parts by weight of the copolymer). (A2): Weight-average molecular weight of 120,000 consisting of 60 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate and 30 parts by weight of 2-hydroxyethyl acrylate.
A reaction product of 100 parts by weight of a 25% ethyl acetate solution of the copolymer of (1) and 7.5 parts by weight of methacryloyloxyethyl isocyanate (0.19 mol based on 100 parts by weight of the copolymer). Energy ray-curable copolymer (B) (B1): 100 parts by weight of a 25% ethyl acetate solution of a copolymer having 90% by weight of butyl acrylate and 10 parts by weight of 2-hydroxyethyl acrylate and having a weight average molecular weight of 400,000. 2.7 parts by weight of methacryloyloxyethyl isocyanate (based on 100 parts by weight of the copolymer,
0.07 mol). (B2): Weight average molecular weight of 400,00 consisting of 80 parts by weight of butyl acrylate, 15 parts by weight of methyl methacrylate, and 5 parts by weight of 2-hydroxyethyl methacrylate.
100 parts by weight of a 25% ethyl acetate solution of 0 copolymer,
1.25 parts by weight of methacryloyloxyethyl isocyanate (0.032 mol per 100 parts by weight of copolymer)
Reaction with. Photopolymerization initiator (C) (C): Irgacure 184 (manufactured by Ciba-Geigy) Copolymer (D) containing no energy ray-polymerizable group (D1): 90 parts by weight of butyl acrylate, 2-hydroxyethyl acrylate 25% ethyl acetate solution of 10 parts by weight of a copolymer having a weight average molecular weight of 400,000. (D2): Weight average molecular weight of 400,00 consisting of 80 parts by weight of butyl acrylate, 15 parts by weight of methyl methacrylate, and 5 parts by weight of 2-hydroxyethyl methacrylate.
25% solution of 0 copolymer in ethyl acetate. (D3): weight-average molecular weight of 400,00 consisting of 55 parts by weight of butyl acrylate, 40 parts by weight of methyl methacrylate, and 5 parts by weight of 2-hydroxyethyl methacrylate.
25% solution of 0 copolymer in ethyl acetate. Energy ray-polymerizable compound (E) (E1): Dipentaerythritol hexaacrylate (E2): Urethane acrylate oligomer (weight average molecular weight about 10,000) Crosslinking agent (F) (F): Coronate L (manufactured by Nippon Polyurethane Co., Ltd.)

[0065]

Example 1 20 parts by weight of the above component (A1), (B1) 8
0 part by weight, 1 part by weight of (C) and 0.5 part by weight of (F) were mixed to obtain an energy ray-curable pressure-sensitive adhesive composition. This energy ray-curable pressure-sensitive adhesive composition was coated with ethylene having a thickness of 80 μm so that the coating thickness after drying was 10 μm.
100 ℃ after coating on methacrylic acid copolymer film
And dried for 1 minute to obtain an adhesive sheet.

Using the obtained pressure-sensitive adhesive sheet, "180 ° peeling adhesive force", "expandability (expansion rate)", "alignment", "residual particles" and "pickup force"
Was evaluated as described above. The results are shown in Table 1.

[0067]

Example 2 33 parts by weight of the above component (A1), (B1) 6
The same operation as in Example 1 was performed except that 7 parts by weight, 1 part by weight of (C) and 0.5 parts by weight of (F) were used. The results are shown in Table 1.

[0068]

Example 3 20 parts by weight of the above component (A1), (B2) 8
The same operation as in Example 1 was performed except that 0 part by weight, 1 part by weight of (C) and 0.5 part by weight of (F) were used. The results are shown in Table 1.

[0069]

Example 4 33 parts by weight of the above component (A1), (B2) 6
The same operation as in Example 1 was performed except that 7 parts by weight, 1 part by weight of (C) and 0.5 parts by weight of (F) were used. The results are shown in Table 1.

[0070]

Example 5 20 parts by weight of the above component (A2), (B1) 8
The same operation as in Example 1 was performed except that 0 part by weight, 1 part by weight of (C) and 0.5 part by weight of (F) were used. The results are shown in Table 1.

[0071]

Example 6 20 parts by weight of the above component (A2), (B2) 8
The same operation as in Example 1 was performed except that 0 part by weight, 1 part by weight of (C) and 0.5 part by weight of (F) were used. The results are shown in Table 1.

[0072]

Example 7 20 parts by weight of the above component (A1), (B1) 8
The same operation as in Example 1 was carried out except that 0 parts by weight, (C) 1 part by weight, (E1) 5.0 parts by weight and (F) 0.5 parts by weight were used. The results are shown in Table 1.

[0073]

Example 8 20 parts by weight of the above component (A1), (B1) 8
The same operation as in Example 1 was carried out except that 0 parts by weight, (C) 1 part by weight, (E2) 5.0 parts by weight, and (F) 0.5 parts by weight were used. The results are shown in Table 1.

[0074]

Comparative Example 1 The same operation as in Example 1 was carried out except that the component (A1) was not used and the component (B1) was used in a proportion of 100 parts by weight. The results are shown in Table 1.

[0075]

Comparative Example 2 The same operation as in Example 3 was carried out except that the component (A1) was not used and (B2) was used in a proportion of 100 parts by weight. The results are shown in Table 1.

[0076]

Comparative Example 3 The same operation as in Example 1 was carried out except that the component (B1) was not used and (A1) was used in a proportion of 100 parts by weight. The results are shown in Table 1.

[0077]

Comparative Example 4 The same operation as in Example 5 was carried out except that the component (B1) was not used and (A2) was used in a proportion of 100 parts by weight. The results are shown in Table 1.

[0078]

Comparative Example 5 (C) 1 part by weight, (D1) 45 parts by weight,
The same operation as in Example 1 was carried out except that 55 parts by weight of (E1) and 0.5 parts by weight of (F) were used. The results are shown in Table 1.

[0079]

Comparative Example 6 (C) 1 part by weight, (D2) 45 parts by weight,
The same operation as in Example 1 was carried out except that 55 parts by weight of (E2) and 0.5 parts by weight of (F) were used. The results are shown in Table 1.

[0080]

[Comparative Example 7] (C) 1 part by weight, (D3) 45 parts by weight,
The same operation as in Example 1 was carried out except that 55 parts by weight of (E1) and 0.5 parts by weight of (F) were used. The results are shown in Table 1.

[0081]

Comparative Example 8 (A1) 70 parts by weight, (C) 1 part by weight,
The same operation as in Example 1 was carried out except that (D2) 30 parts by weight and (F) 0.5 parts by weight were used. The results are shown in Table 1.

[0082]

Comparative Example 9 (A1) 30 parts by weight, (C) 1 part by weight,
The same operation as in Example 1 was carried out except that (D2) 70 parts by weight and (F) 0.5 part by weight were used. The results are shown in Table 1.

[0083]

[Table 1]

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Claims (5)

(57) [Claims] 1. An energy ray-polymerizable group-containing compound (A) having a substituent capable of reacting with the functional group per 100 g of an acrylic copolymer having a functional group-containing monomer unit (A).
An energy ray-curable copolymer having an energy ray-polymerizable group in a side chain and having a molecular weight of 50,000 or more, which is obtained by reacting with 2 mol or more, and (B) an acrylic copolymer having a functional group-containing monomer unit. A molecular weight of 50,000 or more having an energy ray-polymerizable group in a side chain, which is obtained by reacting 100 g of the combined product with less than 0.12 mol of an energy ray-polymerizable group-containing compound having a substituent capable of reacting with the functional group. The energy ray-curable pressure-sensitive adhesive composition containing the energy ray-curable copolymer of 1. and containing no acrylic polymer having no energy ray-polymerizable group in its side chain. 2. The energy ray-curable pressure-sensitive adhesive composition according to claim 1, further comprising (C) a photopolymerization initiator. 3. A pressure-sensitive adhesive sheet comprising the substrate, on which the energy ray-curable pressure-sensitive adhesive composition according to claim 1 or 2 is applied. 4. The adhesive sheet according to claim 3, which is used as an adhesive sheet for wafer processing. 5. The pressure-sensitive adhesive sheet according to claim 3, which is used as a pressure-sensitive adhesive sheet for surface protection.